1. Field of the Invention
The present invention relates to an image processing program suitable for application to processing for rendering an object image having slopes and bumps on a two-dimensional monitor screen, such as the case of a green in a golf game, a computer-readable recording medium having stored therein the image processing program, an image processing method, and an image processing apparatus.
2. Description of the Related Art
In the past, various video games have been provided in which a player can operate a character in a virtual space created by executing a game program.
In these games, for example, the ground upon which a character stands is often modeled by a flat object, which has no slopes or bumps, and rendered two-dimensionally on a monitor apparatus. This is done because in modeling the ground so that it has slopes and bumps, it is necessary to perform a large amount of additional calculations corresponding to the variation in the slopes or bumps of the ground surface, for example collision analysis (contact judgment) of contact area between the character and ground surface and analysis of the movement of the character in response to the variation in the shape of the ground surface, thereby placing a large load on an image processing apparatus such as a video game machine or personal computer that executes the game program.
In recent years, however, with an increase in the processing speed of processors, there has been a rapid improvement in the processing capability of image processing apparatuses, thereby enabling undulation processing, in which a ground surface having slopes and bumps is modeled and rendered, and various real-time processing accompanied by applying of undulation processing. For example, in a golf game, it has become possible to render a green having many and varied slopes and bumps on a monitor apparatus.
Until now, however, although image processing apparatuses have progress to the point at which they can render slopes and bumps using undulation processing, for example, the rendering of a reproduction of the rolling of a golf ball as it follows the slopes and bumps on a green, even when applying undulation processing, because the rendering is done two-dimensionally on a monitor apparatus, it is extremely difficult for a player to visually perceive the condition of a green having such minute and delicate slopes and bumps that it is close to being flat. For this reason, in the case in which a plurality of players are playing a golf game using one monitor apparatus, the actual ground surface condition perceived by a player will depend on the player's seating position.
One method that can be envisioned for solving this problem associated with rendering processing using undulation processing is that, for example, renders on an object surface grid lines formed by joining vertices of a polygon group that forms the object, the spacing between and number of these grid lines being used to cause a player to perceive fine variations in slope or bumps. The term “polygon” used here is the smallest graphical unit making up an object, and is for example a triangle, a rectangle or other polygon.
However, although the above-noted type of grid lines can be used to cause a player to perceive relatively large slopes and bumps in the ground surface via a monitor apparatus, it is difficult with grid lines alone to cause perception of tiny slopes and bumps, for example, on a surface that is substantially flat, because the spacing and number of nearby grid lines is substantially the same.
In a golf game for example to which the above-noted undulation processing is not applied, it can be envisioned that slopes and bumps can be expressed by mapping the turf particles on the green, with the rolling direction of a golf ball being forcibly decided based on this turf particles, in this case because the above-noted image processing apparatus is not applied to undulation processing, it is not possible to reproduce the condition of rolling of the golf ball over minute slops of the green.